Robust Robotic 3-D Drawing Using Closed-Loop Planning and Online Picked Pens

This article develops a flexible and robust robotic system for autonomously drawing on 3-D surfaces. The system takes 2-D drawing strokes and a 3-D target surface (mesh or point clouds) as input. It maps the 2-D strokes onto the 3-D surface and generates a robot motion to draw the mapped strokes using visual recognition, grasp pose reasoning, and motion planning. The system is flexible compared to conventional robotic drawing systems as we do not fix drawing tools to the end of a robot arm. Instead, a robot recognizes and picks up pens online and holds the pens to draw 3-D strokes. Meanwhile, the system has high robustness thanks to the following crafts: First, a high-quality mapping method is developed to minimize deformation in the strokes. Second, visual detection is used to reestimate the drawing tool’s pose before executing each drawing motion. Third, force control is employed to compensate for noisy visual detection and calibration and ensure a firm touch between the pen tip and the surface. Fourth, error detection and recovery are implemented to deal with slippage and other anomalies. The planning and executions are performed in a closed-loop manner until the strokes are successfully drawn. We evaluate the system and analyze the necessity of the various crafts using different real-world tasks. The results show that the proposed system is flexible and robust to generate robotic motion that picks up the pens and successfully draws 3-D strokes on given surfaces.